Magnetic torque control coupling

ABSTRACT

Disclosed is a coupling in which the drive shaft initially picks up the load provided by a driven shaft through a resilient element and subsequently drives the load through a magnetic link between the drive and driven shaft, the magnetic link and hence the degree of torque transfer being controlled by the level of magnetic flux through the link.

United States Patent Whipker 1 1 Apr. 25, 1972 [54] MAGNETIC TORQUECONTROL COUPLING [72] Inventor: Jesse A. Whipker, P.O. Box 361,Columbus, lnd. 47201 [22] Filed: Apr. 5, 1971 [21] Appl.No.: 131,362

52] u.s.c1 ..31o/92,310/s4 511 1111.01. ..H02k49/00 58 Field 61 Search......31o/7s,79,102,110,114,113, 31o/94,92, 152, 95,96,156, 100, 101,171, 114,

[56] References Cited UNITED STATES PATENTS 2,871,383 1/1959 King..3l0/96 3,171,995 3/1965. Ponsy ..3l0/l00 3,573,518 4/1971 Liles....3l0/l56 3,558,945 l/l97l Hulle ..310/l0l Primary Examiner-William M.Shoop, Jr. Assistant Examiner-R. Skudy Attorney-Woodard, Weikart,Emhardt & Naughton [5 7] ABSTRACT Disclosed is a coupling in which thedrive shaft initially picks up the load provided by a driven shaftthrough a resilient element and subsequently drives the load through amagnetic link between the drive and driven shaft, the magnetic link andhence the degree of torque transfer being controlled by the level ofmagnetic flux through the link.

6 Claims, 4 Drawing Figures P'ATENTED APR 2 5 I972 Zia.

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R mw EM V W 4 E m J ATTORNEYS MAGNETIC TORQUE CONTROL COUPLINGBACKGROUND OF THE INVENTION Operation of machinery, such as hammermillsfor example, demand a high starting torque, because of the high inertiaload, and a relatively long acceleration period. Because powerrequirement is relatively high at the initial pick-up of the load, andonly reduced power is needed thereafter, heretofore such applicationshave conventionally required relatively expensive reduced voltageelectric starters. Further, in applications where constant speedelectric motors are utilized, a relatively simple overload responsivemeans, such as a fuse, is satisfactory, however, where a variable speedmotor provides the drive, at low speed the motor is capable of producingtorque sufficient to shear or otherwise damage the driven equipmentshould an abnormal obstruction or jamming of the apparatus occur.Material transfer augers utilized on farm machinery are examples ofequipment of the type referred to. In such equipment attempts have inthe past been made to solve the problem by using shear pins in the powertrain for the auger. This solution leaves much to be desired for theshear pins are often difficult and time consuming to replace and areoften replaced by steel non-shear pins or by pins which shear only underloads too large.

The concept of the present invention utilizes a spring loaded, magneticlink between the drive member and the driven member with the torquetransfer between the members being dependent on the level ofenergization of electromagnet producing the flux linkage across themagnetic elements. The apparatus is relatively simple, acts as a safetydevice for overloads and can be used as a speed control when used inconjunction with a tachometer generator and relay meter.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERREDEMBODIMENT Referring initially to FIG. 1, the coupling assembly includesa drive member which takes the form of a drive shaft and a driven memberin the form of the driven shaft 11, the shafts being coaxial. Rigidlyattached to the driven shaft 11 is a magnetically permeable member13'around which is wrapped a direct current coil 14 and provided with aportion presenting a flat, circular face 14a. A bearing 16 in the member13 journals for free rotation the extending end of the shaft 10. Afurther bearing permits the shaft 11 and attached member 13 to rotatefreely with respect to the stationary, magnetically permeable disc 17.The stationary disc is rigidly attached to a magnetically permeableseries of bars 18 which extend parallel to the shafts l0 and 11 arerigidly attached to a stationary, magnetically permeable disc 19 whichis similar in configuration to the disc 17. A magnetically permeablemember 21, which is provided with a portion providing a flat circularface 21a spaced from an opposing the surface 14a, is journaled in abearing 25 carried by disc 19.

A direct current coil 22 is wrapped about the member 21, however it issupported on, or secured to, the stationary disc 19. A bearing 20journals the member 21 upon the drive shaft 10, enabling the shaft 10 torotate freely with respect to the member 21. The windings l4 and 22 aresupported on the stationary portion of the structure and no slip ringsor brushes are necessary to energize them..Extending outwardly from thefaces 21a and 14a are pole pieces 23 and 24. The windings l4 and 22 areoriented so that the pole pieces 23 and 24are of opposite polarity whena D.C. voltage is impressed on the coils. Adjacent the pole pieces 23and 24 and extending between the face portions 21a and 14a arenon-magnetically permeable bars 26 which serve to brace the assembly.

Referring primarily to FIGS. 1 and 2, it will be evident that each ofthe adjacent pole pieces 23 and 24 are spanned by a magneticallypermeable armature bar 31. Freely supported within apertures in each ofthe several pairs of armatures 31 are elements in the form of rods 32which, by means of the shoulders 32a on the rods, have a lost-motionconnection with the armatures, that is, a limited amount of axial motionof the rod 32 occurs before the shoulders 32a break the armatures 31away from their respective pole pieces.

The central portion of the rod 32 is reduced somewhat in diameter andfreely accommodated on this intermediate portion is a pick-up member 34.Compression springs 36 extend between the rod and the member 34 andserve to bias the member 34 to a central position on the shaft. Themember 34 has abutments 37 extending from its opposite sides as mayparticularly be seen in FIG. 1.

As may be seen in FIG. 1, the abutments 37 are adapted to be engaged byabutments 38 extending from the circumference of a disc shaped member 39(FIG. 3). As will be particularly evident from FIG. 3, the abutments 38are spaced about the periphery of the member 39 and the member 39 itselfis rigidly attached to the drive shaft 10 and rotates with the shaft. Asmay best be seen in FIG. 4 the peripheral area of the member 39 isprovided with an annular groove 41 which freely accommodates thedepending portion 34a of the pick-up member 34, the extension of theportion 34a into the groove 41 serving to stabilize the member 34 andthe rod 32. As will be apparent from a comparison of FIGS. 1 and 2, therods 32 extend generally tangential to the central, disc shaped member39 and while three rod and armature assemblies are disclosed, it will beunderstood that more might be utilized, with correspondingly additionalarmatures and pole pieces provided on a disc shape member of largerdiameter.

In operation, with the drive shaft rotating in the direction indicatedby the arrow in FIG. 1, the member 39 will be rotated, engaging theabutments 38 with the adjacent abutments 37 on the collar or pick-upmember 34. This initial engaging motion of the member 39 moves themember 34 along the rod 32 compressing the spring 36, the motion of themember 34 on the rod being upwardly as viewed in FIG. 1. As the spring36 is compressed, during this motion the rod 32 will be moved throughthe springs 36 until the shoulder 320 on the rod engages the armature31. Thereupon, the armature 31 will be moved and movement of thearmaturewill pull along the pole pieces 23 and 24, rotating the members 19 and17 and consequently rotating the driven shaft 11 in the same directionas the rotation of the drive shaft 10. This motion impulse through thearmature 31 will have a duration dependent upon the mount of magneticflux linking the armature with the members l9 and 17, the path of themagnetic flux being indicated by a broken line in the upper portion ofFIG. 1. As the abutments 38 pass beneath and away from the abutments 37upon continued rotation of the member 39 the springs 36 will againcenter the collar 34 on the rod 32 and the abutments 37 carried by thecollar'will again be in position for engagement with the next set ofabutments 38 onthe members 39 as rotation continues. It may thus be seenthat motion impulses are transferred to the driven shaft 11 and theseimpulses have a magnitude which is dependent upon the D.C. voltageapplied to the coils Hand 14.

It will be evident from a comparison of FIGS. 1 and 2 that for rotationin one direction only one end of the rods and one set of armatures andpole'pieces are used for each rod assembly, and when rotation isopposite in direction to that shown in FIG. 1 the armatures and oppositeends of the rods 32 will be utilized to provide motion impulses to thedriven shaft 11. The apparatus can thus be driven in either directionand the driven shaft output will correspond in direction to that of thedrive shaft. It will be understood that in applications where rotationis to be transmitted to the driven shaft in only onedirection,transposing the position of the armature and rod shoulders which engagethe armature at one end of the rod assemblies will permit both ends ofthe rod assemblies to be utilized to transmit motion and the capacity ofthe apparatus could be increased.

What is claimed is: r

1. An electromagnetic power transfer coupling comprising a drive memberand a driven member, a series of spaced abutments carried by the drivemember, electromagnetic means carried by said driven member including anarmature linking the magnetic flux generated by energization of saidelectromagnetic means, an element having a lost-motion connection withsaid armature, a motion pick-up member having abutments thereon adaptedto be engaged by said drive member carried abutments, said pick-upmember being supported on said armature-connected element, resilientmeans extending between said pick-up member and said element biasingsaid pick-up member abutments toward engagement with said drive membercarried abutments, whereby upon motion of said drive member saidabutments will engage thereby transmitting motion through said resilientmeans to said pickup member and to said armature, and through saidarmature to said electromagnetic means and said driven member, with thekinetic energy transferred through said coupling being determined by thelevel of energization of said electromagnetic means.

2. A coupling as claimed in claim 1 in which said drive member takes theform of a rotating shaft and said driven member is a shaft adapted forrotation coaxially with said drive shaft, and said electromagnetic meansincludes two spaced pole-pieces supported on said driven shaft with saidarmature spanning said pole pieces and said drive shaft carriedabutments, armature-connected element and pick-up member being disposedbetween said spaced pole-pieces.

3. A coupling as claimed in claim 2 in which said electromagnetic meansfurther includes coils associated with each of said pole pieces toproduce opposite polarity therein, with the level of kinetic energytransferred by said coupling thus being determined by the DC. voltageapplied to said coils.

4. A coupling as claimed in claim 2 in which said drive shaft carriedabutments extend from the circumference of a discshaped member carriedby and rotated with the drive shaft, said armature-connected elementtakes the form of a rod extending generally tangential to saiddisc-shaped member and said pick-up member is a collar freely slidablealong said rod, and said resilient means takes the form of a coiledcompression spring encircling said rod and extends between a shoulder onsaid rod and said collar to thereby urge said collar into a positionalong said shaft permitting said abutment carried by the collar to beengaged by said drive shaft carried abutments.

5. A coupling as claimed in claim 4 in which said discshaped member isprovided with a circumferential groove and said collar is provided witha depending portion which is accommodated within said groove tostabilize said collar upon said rod.

6. A coupling as claimed in claim 4 in which a further pair ofelectromagnetic spaced pole pieces are spanned by a further armaturealso having a lost motion connection with said rod at the end of the rodremote from its connection to said first mentioned armature wherebytorque is transferred to said driven shaft by said drive shaft in eitherdirection of axial rotation of said drive shaft.

1. An electromagnetic power transfer coupling comprising a drive memberand a driven member, a series of spaced abutments carried by the drivemember, electromagnetic means carried by said driven member including anarmature linking the magnetic flux generated by energization of saidelectromagnetic means, an element having a lost-motion connection withsaid armature, a motion pick-up member having abutments thereon adaptedto be engaged by said drive member carried abutments, said pick-upmember being supported on said armature-connected element, resilientmeans extending between said pick-up member and said element biasingsaid pick-up member abutments toward engagement with said drive membercarried abutments, whereby upon motion of said drive member saidabutments will engage thereby transmitting motion through said resilientmeans to said pick-up member and to said armature, and through saidarmature to said electromagnetic means and said driven member, with thekinetic energy transferred through said coupling being determined by thelevel of energization of said electromagnetic means.
 2. A coupling asclaimed in claim 1 in which said drive member takes the form of arotating shaft and said driven member is a shaft adapted for rotationcoaxially with said drive shaft, and said electromagnetic means includestwo spaced pole-pieces supported on said driven shaft with said armaturespanning said pole pieces and said drive shaft carried abutments,armature-connected element and pick-up member being disposed betweensaid spaced pole-pieces.
 3. A coupling as claimed in claim 2 in whichsaid electromagnetic means further includes coils associated with eachof said pole pieces to produce opposite polarity therein, with the levelof kinetic energy transferred by said coupling thus being determined bythe D.C. voltage applied to said coils.
 4. A coupling as claimed inclaim 2 in which said drive shaft carried abutments extend from thecircumference of a disc-shaped member carried by and rotated with thedrive shaft, said armature-connected element takes the form of a rodextending generally tangential to said disc-shaped member and saidpick-up member is a collar freely slidable along said rod, and saidresilient means takes the form of a coiled compression spring encirclingsaid rod and extends between a shoulder on said rod and said collar tothereby urge said collar into a position along said shaft permittingsaid abutment carried by the collar to be engaged by said drive shaftcarried abutments.
 5. A coupling as claimed in claim 4 in which saiddisc-shaped member is provided with a circumferential Groove and saidcollar is provided with a depending portion which is accommodated withinsaid groove to stabilize said collar upon said rod.
 6. A coupling asclaimed in claim 4 in which a further pair of electromagnetic spacedpole pieces are spanned by a further armature also having a lost motionconnection with said rod at the end of the rod remote from itsconnection to said first mentioned armature whereby torque istransferred to said driven shaft by said drive shaft in either directionof axial rotation of said drive shaft.